Every minute spent in one to 10-minute bouts of high-intensity activity was as beneficial to Body Mass Index (BMI) as every minute in longer bouts of 10 or more minutes of higher-intensity exercise, the study found. BMI is a number calculated from a person's weight and height and is an indicator of body fatness used to screen for obesity.

"What we learned is that for preventing weight gain, the intensity of the activity matters more than duration," study author Jessie X. Fan, a University of Utah professor, said in a news release.

Federal guidelines recommend adults get 150 minutes weekly of moderate-to-vigorous physical activity, accumulated during bouts lasting at least 10 minutes each. But the study found fewer than 4 percent of Americans age 20 to 59 reach this guideline.

"Knowing that even short bouts of brisk activity can add up to a positive effect is an encouraging message for promoting better health," Fan said.

The study said those short bouts of activity can include exercise like brisk walking and climbing stairs.

You can contract health writer James T. Mulder at jmulder@syracuse.com or (315) 470-2245. Follow him at twitter.com/JamesTMulder